1. Field of Invention
The present invention relates to a pry bar for removing boards from floors, siding, walls, and other areas where boards are attached to a structure. The pry bar provides an effective and more convenient tool for removing boards while minimizing damage to the boards so that they may be reused.
2. Description of the Prior Art
Pry bars are widely used to remove or dislodge objects. Pry bars typically are operated by hand and consist of a long handle, a fulcrum, and a pry arm shorter in length than the handle. The user of a pry bar applies force to the handle which in turn is translated across the fulcrum to the pry arm. The resulting force at the pry arm is greater than the force applied by the user because the pry arm is of a shorter length than the handle. Thus, a pry bar operates by magnifying the force applied by a user and, as a result, enables the user to remove or dislodge objects that cannot be removed or dislodged by hand.
Pry bars have been modified over the years to increase ease of use, to perform additional functions, and to suit specific purposes. For instance, U.S. Pat. No. Des. 236,872 (Froehlich) describes a pry bar specifically designed to remove boards. The Froehlich pry bar is comprised of a handle, a crossbar which acts as the fulcrum, and a pair of short, spaced pry arms which form an acute angle with the handle. To operate the pry bar, the pry arms are placed behind the board to be removed, and the crossbar is placed against the stud holding the board. A force is applied to the handle which in turn is magnified at the short pry arms, thus generating enough force to remove the board. While such a design is adequate to remove boards under most circumstances, the design is limited because the acute angle between the handle and pry arms precludes a user from exerting body weight to assist in the removal of horizontal boards. For example, if the Froehlich pry bar is used to remove a board from a floor, the user cannot exert body weight against the handle because of the acute angle between the handle and pry arms. In this circumstance, an obtuse angle between the handle and pry arms would allow the user to exert body weight against the handle, thus decreasing the effort the user must generate to remove the board.
Also, the Froehlich design only provides a single pair of pry arms of a given length, which limits the amount of force that the user can generate at the pry arms. More specifically, a user generates a given amount of torque when the user applies force to the pry bar handle. Because torque is equal to force times distance, the force generated at the end of the pry arms is equal to the torque divided by the length of the pry arms measured from the crossbar. As a result, for a given force applied by a user, the force generated at the tip of the pry arms increases if the length of the pry arms is decreased. In other words, decreasing the length of the pry arms increases the leverage that a user can generate with the pry bar, but the pry arm length must be sufficient to remove the board without damage. In this respect, a pry bar with multiple length pry arms would provide more versatility.
Finally, the Froehlich design does not include a feature which can remove nails, which is the primary mechanism for attaching boards.
U.S. Pat. No. 1,309,734 (Hemfling) also describes a pry bar specifically designed to remove boards. Similar to Froehlich, the Hemfling pry bar is comprised of a handle, a crossbar, and a pair of short, spaced pry arms. Unlike Froehlich, the Hemfling pry bar has a claw for removing nails, and the angle between the handle and pry arms is obtuse. Thus, Hemfling improves upon Froehlich in that the Hemfling pry bar can remove nails and allows a user to exert body weight when removing horizontal boards. However, similar to Froehlich, Hemfling is limited because it provides only a single pair of pry arms of a given length. In addition, the Hemfling design cannot be used to remove boards under certain circumstances because of the obtuse angle between the handle and pry arms. For example, if a floor board located near a wall must be removed and the only access to the bottom surface of the board is between the board and wall, the Hemfling pry bar cannot be used because the wall will prevent the handle from traveling through a sufficient range of motion to dislodge or remove the board. A similar problem occurs if a horizontal wall board located near the floor must be removed and the only access to the back surface of board is between the board and floor. A pry bar with an acute angle between the handle and pry arms would address this design limitation of Hemfling.
Finally, U.S. Pat. No. 2,680,003 (Feinstein) describes a pry bar specifically designed to remove boards. The Feinstein pry bar also is comprised of a handle, a cross bar, and a pair of short, spaced pry arms. While the Feinstein pry bar provides the same advantages over Froehlich that Hemfling provides, Feinstein also suffers from the same design limitations as Hemfling as a result of the single pair of pry arms and the obtuse angle between the handle and pry arms.